The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ($B_0 = 12.2$ T), compact ($R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ($H_{98,y2} = 0.7$) and, with the nominal assumption of $H_{98,y2} = 1$, SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ($\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$), high temperature ($\langle T_e \rangle \approx 7$ keV) and high power density ($P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.

SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$, a normalized density of $n_G=0.37$ and a safety factor of $q_{95}\approx 3.4$, providing a comfortable margin to their respective disruption limits. Further, a low beta poloidal $\beta _p=0.19$ at the safety factor $q=2$ surface reduces the drive for neoclassical tearing modes, which together with a frozen-in classically stable current profile might allow access to a robustly tearing-free operating space. Although the inherent stability is expected to reduce the frequency of disruptions, the disruption loading is comparable to and in some cases higher than that of ITER. The machine is being designed to withstand the predicted unmitigated axisymmetric halo current forces up to 50 MN and similarly large loads from eddy currents forced to flow poloidally in the vacuum vessel. Runaway electron (RE) simulations using GO+CODE show high flattop-to-RE current conversions in the absence of seed losses, although NIMROD modelling predicts losses of ${\sim }80$ %; self-consistent modelling is ongoing. A passive RE mitigation coil designed to drive stochastic RE losses is being considered and COMSOL modelling predicts peak normalized fields at the plasma of order $10^{-2}$ that rises linearly with a change in the plasma current. Massive material injection is planned to reduce the disruption loading. A data-driven approach to predict an oncoming disruption and trigger mitigation is discussed.

In order to inform core performance projections and divertor design, the baseline SPARC tokamak plasma discharge is evaluated for its expected H-mode access, pedestal pressure and edge-localized mode (ELM) characteristics. A clear window for H-mode access is predicted for full field DT plasmas, with the available 25 MW of design auxiliary power. Additional alpha heating is likely needed for H-mode sustainment. Pressure pedestal predictions in the developed H-mode are surveyed using the EPED model. The projected SPARC pedestal would be limited dominantly by peeling modes and may achieve pressures in excess of 0.3 MPa at a density of approximately 3 × 1020 m−3. High pedestal pressure is partially enabled by strong equilibrium shaping, which has been increased as part of recent design iterations. Edge-localized modes (ELMs) with >1 MJ of energy are projected, and approaches for reducing the ELM size, and thus the peak energy fluence to divertor surfaces, are under consideration. The high pedestal predicted for SPARC provides ample margin to satisfy its high fusion gain (Q) mission, so that even if ELM mitigation techniques result in a 2× reduction of the pedestal pressure, Q > 2 is still predicted.

While feed efficiency (FE) is a trait of great economic importance to the pig industry, the influence of the intestinal microbiome in determining FE is not well understood. The objective of this experiment was to determine the relative influence of FE and farm of birth on the pig colonic microbiome. Animals divergent in residual feed intake (RFI) were sourced from two geographically distinct locations (farms A + B) in Ireland. The 8 most efficient (low RFI (LRFI)) and 8 least efficient (high RFI, (HRFI)) pigs from farm A and 12 LRFI and 12 HRFI pigs from farm B were sacrificed. Colonic digesta was collected for microbial analysis using 16S ribosomal RNA gene sequencing and also for volatile fatty acid analysis. The α-diversity differed between the farms in this study, with pigs from farm A having greater diversity based on Shannon and InvSimpson measures compared to pigs from farm B (P < 0.05), with no difference identified in either Chao1 or observed measures of diversity (P > 0.05). In the analysis of β-diversity, pigs clustered based on farm of birth rather than RFI. Variation in the management of piglets, weight of the piglets, season of the year, sanitary status and dam dietary influence could potentially be causative factors in this large variation between farms. However, despite significant variation in the microbial profile between farms, consistent taxonomic differences were identified between RFI groups. Within the phylum Bacteroidetes, the LRFI pigs had increased abundance of BS11 (P < 0.05) and a tendency toward increased Bacteroidaceae (P < 0.10) relative to the HRFI group. At genus level, the LRFI pigs had increased abundance of Colinsella (P < 0.05), a tendency toward increased Bacteroides and CF231 (P < 0.10). At species level, Ruminococcus flavefaciens had increased abundance in the LRFI compared to the HRFI animals. In conclusion, while farm of birth has a substantial influence on microbial diversity in the pig colon, a microbial signature indicative of FE status was apparent.

The identification of natural bioactive compounds which can prevent the post-weaning growth check and enhance gastrointestinal health in the absence of in-feed medications is an urgent priority for the swine industry. The objective of this experiment was to determine the effects of increasing dietary inclusion levels of laminarin in the first 14 d post-weaning on pig growth performance and weaning associated intestinal dysfunction. At weaning, ninety-six pigs (8·4 (sd 1·09) kg) (meatline boars × (large white × landrace sows)) were blocked by live weight, litter and sex and randomly assigned to: (1) basal diet; (2) basal + 100 parts per million (ppm) laminarin; (3) basal + 200 ppm laminarin and (4) basal + 300 ppm laminarin (three pigs/pen). The appropriate quantity of a laminarin-rich extract (65 % laminarin) was added to the basal diet to achieve the above dietary inclusion levels of laminarin. After 14 d of supplementation, eight pigs from the basal group and the best-performing laminarin group were euthanised for sample collection. The 300 ppm laminarin group was selected as this group had higher ADFI compared with all other groups and higher ADG than the basal group (P < 0·05). Laminarin supplementation increased villus height in the duodenum and jejunum (P < 0·05). Laminarin supplementation increased the expression of SLC2A8/GLUT8 in the duodenum, SLC2A2/GLUT2, SLC2A7/GLUT7, SLC15A1/PEPT1 and FABP2 in the jejunum and SLC16A1/MCT1 in the colon. Laminarin supplementation reduced Enterobacteriaceae numbers in the caecum (P < 0·05) and increased lactobacilli numbers (P < 0·05), total volatile fatty acid concentrations and the molar proportions of butyrate (P < 0·01) in the colon. In conclusion, 300 ppm laminarin from a laminarin-rich extract has potential, as a dietary supplement, to improve performance and prevent post-weaning intestinal dysfunction.

An experiment was conducted to determine: (1) the effect of excess maternal I supplementation on the thyroid hormone status of the ewe and her progeny; (2) potential mechanisms underpinning the failure of passive transfer associated with excess I and (3) the growing lambs’ response to natural gastrointestinal infection. Twin-bearing ewes received one of two treatments (n 32/treatment group): basal diet (C) or C plus 26·6 mg of iodine/ewe per d (I), supplied as calcium iodate. Ewes were individually fed from day 119 of gestation to parturition. Progeny of I ewes had lower (P<0·01) serum IgG concentrations from 24 h to 28 d postpartum but higher serum IgG concentrations at day 70 postpartum (P<0·05). I supplementation increased the relative expression of Fc receptor, IgA, IgM high affinity and polymeric Ig receptor in the ileum of the lamb at 24 h postpartum; however, thyroid hormone receptor-β (THRB) and β-2-microglobulin (B2M) expression declined (P<0·05). Progeny of I ewes had higher growth rates to weaning (P<0·05) and lower faecal egg count (FEC) for Nematodirus battus (P<0·05) between weeks 6 and 10 postpartum. In conclusion, excess maternal I supplementation negatively affected the thyroid hormone status, serum IgG concentration, ileal morphology and the gene expression of THRB and B2M in the ileum and ras-related protein (RAB) RAB25 and the mucin gene (MUC) MUC1 in the duodenum of the lamb postpartum. These effects were followed by an enhancement of average daily gain and lower N. battus FEC in the pre-weaning period of I-supplemented lambs.

Pork and pork products are recognised as vehicles of Salmonella Typhimurium infection in humans. Seaweed-derived polysaccharides (SWE) and galacto-oligosaccharides (GOS) have shown to exhibit antimicrobial, prebiotic and immunomodulatory activity. The objective of this study was to assess the effects of dietary GOS and SWE supplementation on reducing S. Typhimurium numbers and intestinal inflammation in vivo. In total, 30 pigs (n=10/treatment, BW 30.9 kg) were randomly assigned to three dietary treatments: (1) basal diet; (2) basal diet+2.5 g GOS/kg diet; (3) basal diet+SWE (containing 180 mg laminarin/kg diet+340 mg fucoidan/kg diet). Following an 11-day dietary adaptation period, pigs were orally challenged with 108 colony-forming units/ml S. Typhimurium (day 0). Pigs remained on their diets for a further 17 days and were then sacrificed for sample collection. The SWE supplementation did not affect S. Typhimurium numbers on days 2 and 4 post-challenge but reduced S. Typhimurium numbers in faecal samples collected day 7 post-challenge (−0.80 log gene copy numbers (GCN)/g faeces) and in caecal and colonic digesta (−0.62 and −0.98 log GCN/g digesta, respectively; P<0.05) compared with the control treatment. Lactobacillus numbers were increased in caecal and colonic digesta after GOS supplementation (+0.70 and +0.35 log GCN/g digesta, respectively; P<0.05). In colonic tissue, both GOS and SWE supplementation resulted in reduced messenger RNA expression levels of interleukin (IL)-6, IL-22, tumour necrosis factor-α and regenerating islet-derived protein 3-γ (P<0.05). It can be concluded that dietary supplementation of SWE reduced faecal and intestinal S. Typhimurium numbers compared with the basal diet, whereas dietary GOS supplementation increased Lactobacillus numbers in caecal and colonic digesta but did not affect S. Typhimurium numbers. Supplementation of GOS and SWE reduced the gene expression of pro-inflammatory cytokines in colonic tissue of pigs after the experimental S. Typhimurium challenge.

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.

The algal polysaccharides laminarin (LAM) and fucoidan (FUC) have potent anti-inflammatory activities in the gastrointestinal tract. Our objective was to examine the impact of prior consumption of LAM and/or FUC on pathology and inflammation following a dextran sodium sulfate (DSS) challenge in pigs. Pigs (n 7/group) were assigned to one of five experimental groups for 56 d. From 49–55 d, distilled water or DSS was administered intragastrically. The experimental groups were: (1) basal diet + distilled water (control); (2) basal diet + DSS (DSS); (3) basal diet + FUC + DSS (FUC + DSS); (4) basal diet + LAM + DSS (LAM + DSS); and (5) basal diet + LAM + FUC + DSS (LAMFUC + DSS). The DSS group had decreased body-weight gain (P < 0·05) and serum xylose (P < 0·05), and increased proximal colon pathology score (P < 0·05), diarrhoeal score (P < 0·001) and colonic Enterobacteriaceae (P < 0·05) relative to the control group. The FUC + DSS (P < 0·01), LAM + DSS (P < 0·05) and LAMFUC + DSS (P < 0·05) groups had improved diarrhoeal score, and the LAMFUC + DSS (P < 0·05) group had improved body weight relative to the DSS group. The FUC + DSS group (P < 0·001), LAM + DSS group (P < 0·05) and LAMFUC + DSS group (P < 0·001) had lower IL-6 mRNA abundance relative to the DSS group. The LAM + DSS group had reduced Enterobacteriaceae in proximal colon digesta relative to the DSS group (P < 0·05). In conclusion, FUC or a combination of FUC and LAM improved body-weight loss, diarrhoeal scores and clinical variables associated with a DSS challenge in pigs, in tandem with a reduction in colonic IL-6 mRNA abundance.

A 59-year-old man presented with the acute onset of paresthesias and pain in the left neck, face, and forehead. On subsequent investigation he was found to have a subadventitial type of carotid artery dissection, producing an ipsilateral Horner's syndrome with normal carotid angiography. MRI imaging of the neck structures, using fat saturation technique, showed the subadventitial dissection, sparing the vessel lumen. MRI offers a non-invasive method of diagnosis and follow-up for carotid artery dissection.

The experiment investigated the effect of maternal dietary supplementation of seaweed-derived polysaccharides (SDP) (–SDP v. +SDP, n   20) from day 83 of gestation until weaning (day 28) on selected sow faeces and piglet digesta microbiota populations, piglet small-intestinal morphology, and intestinal nutrient transporter and inflammatory cytokine gene expression at birth, 48 h after birth and weaning. The effect of maternal dietary treatment on the piglet gene expression profile of inflammatory cytokines in the colon following a lipopolysaccharide (LPS) challenge was also investigated. Dietary SDP reduced sow faecal Enterobacteriaceae gene numbers at parturition. Small-intestinal morphology, nutrient transporter and cytokine gene expression in newborn piglets did not differ between maternal dietary treatments (P > 0·10). At 48 h after birth, sodium–glucose-linked transporter 1 gene expression was down-regulated in the ileum of piglets suckling the SDP-supplemented sows compared with those suckling the basal sows (P = 0·050). There was a SDP × LPS challenge interaction on IL-1 and IL-6 gene expression in the colon of piglets (P < 0·05). The gene expression of IL-1 and IL-6 was down-regulated in the LPS-challenged colon of piglets suckling the SDP sows compared with those suckling the basal sows (P < 0·05). However, there was no difference in IL-1 and IL-6 gene expression in the unchallenged colon between treatment groups. At weaning, piglets suckling the SDP-supplemented sows had increased villus height in the jejunum and ileum compared with those suckling the basal-fed sows (P < 0·05). In conclusion, maternal dietary SDP supplementation enhanced the immune response of suckling piglets and improved gut morphology, making them more immune competent to deal with post-weaning adversities.

In the present study, a 2 × 2 factorial arrangement was conducted to investigate the effect of maternal supplementation with seaweed extracts ( − SWE v. +SWE, n 20) from day 83 of gestation until weaning (day 28) on post-weaning (PW) growth performance, faecal score, faecal enterotoxigenic Escherichia coli (ETEC) toxin quantification, intestinal histology and cytokine mRNA of unchallenged and ETEC-challenged pigs. Pigs were ETEC challenged on day 9 PW. There was a maternal treatment × challenge (SWE × ETEC) interaction effect on growth performance and faecal score (P< 0·05). Pigs from SWE-supplemented sows and ETEC-challenged (SE) had higher average daily gain (ADG) during 0–13 d PW and reduced faecal score during 0–72 h post-challenge than those from basal-fed sows and ETEC-challenged (BE) (P< 0·05). However, there was no difference between unchallenged pigs from the SWE-supplemented sows (SC) and basal-fed sows (BC) (P>0·10). Pigs from the SWE-supplemented sows had reduced heat-labile enterotoxin gene copy numbers than those from the basal-fed sows (P< 0·05). Maternal SWE supplementation increased the villus height in the ileum of pigs (P< 0·05). There was a SWE × ETEC interaction effect (P< 0·05) on IL-6 mRNA and a SWE × gastrointestinal (GI) region interaction effect (P< 0·05) on transforming growth factor-β1 (TGF-β1) and TNF-α mRNA. IL-6 mRNA was down-regulated in SC pigs than BC pigs (P< 0·05). However, there was no difference in IL-6 mRNA between SE and BE pigs. The mRNA of TGF-β1 and TNF-α was down-regulated in the colon of pigs from the SWE-supplemented sows compared with those from the basal-fed sows (P< 0·05). However, there was no difference in TGF-β1 and TNF-α mRNA in the ileum between the pigs from the SWE-supplemented sows and basal-fed sows. In conclusion, maternal SWE supplementation improves ADG and the aspects of GI health of weaned pigs following an ETEC challenge.

In the present study, two experiments were conducted to (1) evaluate the effect of laminarin and/or fucoidan on ileal morphology, nutrient transporter gene expression and coefficient of total tract apparent digestibility (CTTAD) of nutrients and (2) determine whether laminarin inclusion could be used as an alternative to ZnO supplementation in weaned pig diets. Expt 1 was designed as a 2 × 2 factorial arrangement, comprising four dietary treatments (n 7 replicates, weaning age 24 d, live weight 6·9 kg). The dietary treatments were as follows: (1) basal diet; (2) basal diet+300 ppm laminarin; (3) basal diet+240 ppm fucoidan; (4) basal diet+300 ppm laminarin and 240 ppm fucoidan. There was an interaction between laminarin and fucoidan on the CTTAD of gross energy (GE) (P< 0·05) and the expression of sodium–glucose-linked transporter 1 (SGLT1/SLC5A1) and GLUT1/SLC2A1 and GLUT2/SLC2A2 (P< 0·05) in the ileum. The laminarin diet increased the CTTAD of GE and increased the expression of SGLT1, GLUT1 and GLUT2 compared with the basal diet. However, there was no effect of laminarin supplementation on these variables when combined with fucoidan. Expt 2 was designed as a complete randomised design (n 8 replicates/treatment, weaning age 24 d, live weight 7·0 kg), and the treatments were (1) basal diet, (2) basal diet and laminarin (300 ppm), and (3) basal diet and ZnO (3100 ppm, 0–14 d, and 2600 ppm, 15–32 d post-weaning). The laminarin diet increased average daily gain and gain:feed ratio compared with the basal diet during days 0–32 post-weaning (P< 0·01) and had an effect similar to the ZnO diet. These results demonstrate that laminarin provides a dietary means to improve gut health and growth performance post-weaning.

Seaweed extracts (SWE) rich in laminarin and fucoidan have shown promise as a supplement for weaned piglets. However, successful application in pig nutrition depends on their bioactivity in the presence of additives such as ZnO. In the present study, a 2 × 2 factorial experiment was carried out to investigate the effect of the interaction between SWE and ZnO on the growth performance, digestibility and faecal characteristics of 192 weaned piglets (6·5 kg). The piglets were penned in groups of 4 (n 12 pens). The study consisted of two phases after weaning: a starter diet period from the day of weaning (0 d) to 21 d and a transition diet period from 21 to 40 d. The dietary treatments were as follows: (1) control diet; (2) control diet+ZnO; (3) control diet+SWE; (4) control diet+ZnO+SWE. Diets containing ZnO improved the faecal consistency of the piglets throughout the experimental period (0–40 d). An effect of the interaction between ZnO and SWE on several variable was observed. The diet containing only SWE or ZnO improved the feed conversion efficiency of the piglets during the transition diet period; however, this effect was not observed when the diet containing both ZnO and SWE was fed. The diet containing only SWE increased the N and organic matter digestibility of the piglets; however, this effect was not observed in the presence of ZnO. An interaction between ZnO and SWE was observed, whereby the faecal counts of Escherichia coli were decreased when piglets were fed the diet containing only SWE, but not when fed the diet containing both SWE and ZnO. In summary, SWE and ZnO improve growth performance when given alone, but not when given in combination. The biological effect of SWE on selected digestibility and faecal characteristics was markedly different when compared with that of ZnO.